Method and device for regulating the concentration of components of additives in a printing process liquid

ABSTRACT

The invention concerns a method for regulating the concentrations of components of additives in a printing process liquid for maintaining predetermined desired concentrations of components of additives in a printing process liquid, wherein the actual concentrations of components are determined followed by redosing of measured components to a predetermined desired concentration. The method is characterized in that the components to be measured are spectroscopically detected. The invention also concerns a device for regulating the concentrations of components of additives in a printing process liquid comprising a measuring means for measuring the concentrations of at least part of the components in the process liquid, comprising a control loop and a means for redosing at least part of the components, wherein the measuring means comprises at least one spectrometer.

BACKGROUND OF THE INVENTION

The invention concerns a method for regulating the concentrations ofcomponents of additives in a printing process liquid, wherein the actualconcentrations of the components are determined and the measuredcomponents are redosed to obtain predetermined desired concentrations,as well as a method for regulating the concentrations of components ofadditives in a printing process liquid using a measuring means formeasuring the concentrations of at least part of the components in theprocess liquid, comprising a control loop and a means for redosing atleast part of the components.

In offset printing machines, the printing plate is wet with an aqueousliquid using a so-called dampening system, such that image areas acceptthe ink in a subsequent processing step, whereas the image-free areasrepel the ink. In addition to water, the aqueous liquid often containsan alcohol mixture, in most cases isopropanol, as well as a chemicalmixture of up to approximately twenty substances (referred to below asan additive). The additive is dosed in concentrations of between 1 and 8vol. % and the alcohol is added in concentrations of between 0.5 and 20vol. %. The concentration of water is therefore between 72 and 98.5 vol.%. If optimized additives are used, alcohol is sometimes completelyomitted. In this case, the additive is also called an alcoholsubstitute. The optimized additive either completely or partiallyassumes the function of the isopropanol. Additives substantially containthe following substance groups:

-   -   surface-active substances such as higher alcohols and tensides        which reduce, in particular, the dynamic surface tension, and        are used, possibly partially, as an isopropanol substitute,    -   buffers, in particular phosphate and citrate buffers which        maintain the pH value of the dampening solution at a constant        value in a range between 4.8 and 5.3,    -   wetting agents such as e.g. glycerine which make the printing        plates hydrophilic,    -   antioxidants as corrosion protection, glycols and glycol ether        which act as solubilizers and keep the above-mentioned substance        groups in the aqueous solution, and    -   substances having a germ-killing effect.

One major problem in offset printing is the insufficient up-time of thevery expensive printing machine, which is typically only approximately80% and is therefore characterized by long down-times. One could e.g.save approximately 35,000.00 Euros per year if the pure productive timeper day of a so-called 64 page rotary offset printing line could merelybe increased by an average of two minutes. New, intensive practicalexaminations have clearly shown that the insufficient up-time of offsetprinting machines is essentially due to the undefined, unknown physicaland chemical composition of the process liquid which, to date, cannot bemeasured and therefore cannot be regulated. These experiments showed, ina particular and in a paradoxical manner, that even if a predeterminedvolumetric mixture of the water and additive components is exactlyrealized, e.g. through precise control of two dosing pumps injectinge.g. volumes of 97 vol % water and 3 vol % additive into the processliquid, a much lower value is actually present in the process liquidcircuit, e.g. 0.8 vol % of additive. Even more surprising, analyses haveshown that the original percentage composition of the individualcomponents of the additive in the dampening solution circuit do notcorrespond to the originally targeted composition which was injected bythe dosing pumps through controlled feeding. Processes take place(“cannibalistic effects”), with which the components of the additive areconsumed during the printing process to a greater or lesser degreedespite the fact that they are added periodically in accordance withtargeted concentration proportions. Current, conventional offsetprinting technology of feeding the additive concentrate in the form ofone single chemical mixture which contains all required chemicalcomponents with precisely predetermined concentrations and whosecomposition depends on the application of pressure, i.e. roller offset,sheet-fed offset or newspaper printing and on the type of machine,paper, ink, in the dampening solution circuit of a printing machine, isan inadequate procedure which does not meet modern requirements for highup-time in the offset process. Although these disadvantages can becompensated for to a certain degree in printing with alcohol through theaddition of higher concentrations of isopropanol, as is currentpractice, this method cannot be regarded as a technical solution for thefuture, since isopropanol, being a solvent and volatile component(VOC=volatile organic compound), is prohibited in offset printing inmany US states, subject to strict laws for emission reduction in Europe,and even fined in Switzerland with a penalty tax, the so-called“Lenkungsabgabe”, which is detrimental to the economics of the printingprocess. For political environmental reasons and, in particular, toprotect the health of the printers at their workplace, isopropanol orother solvents must be substantially reduced or completely eliminated infuture printing processes. The concentrations of alcohol in thedampening solution are currently generally between 6% and 20% andfacilitate the use of so-called film dampening devices in roller andsheet-fed offset printing. In accordance with prior art, the filmdampening devices comprise several rollers which are coated with rubbermixtures and/or metals and which are rotated together in contact witheach other under slight pressure to transport the dampening solution, inthe form of a film of adjustable film thickness, to the printing plate.This transport process is facilitated by the addition of isopropanol dueto the reduction of surface tension of the liquid film caused thereby.In addition to conventional film dampening devices, contact-freeoperating systems, in particular, spray dampening devices operating withnozzles, or dampening devices comprising rollers jacketed with plush arealso used. In these cases, the dampening means is transported withoutcontinuous liquid film, and use of alcohol may therefore be omitted. Thenew inventive method is also of great importance for conventionaldesigns, since it permits optimum composition of chemicals in thedampening solution.

To meet the legal constraints regarding the ban of isopropanol, othersolvents have been marketed, in particular in the U.S.A. This has notbeen the case in Europe, since this solution does not eliminate the useof solvents. Moreover, some of the other solvents are assumed to causecancer or be detrimental to health and therefore do not constitute analternative to alcohol.

A real alternative to alcohol are the so-called tensides which achievecomparable advantages with regard to the wetting properties of thedampening solution on the rollers of the dampening device. It must benoted, in particular, that tensides are not VOCs. Experience has shownthat these positive tenside properties may be utilized only if therequired targeted concentrations can be accurately met. In the currentlyused conventional alcohol-free methods, tensides produce undesired foamsand emulsification of ink and dampening solution which reduces quality,such that, in many practical applications, printing without alcoholfails and must be replaced by printing with alcohol. This is furthercomplicated by the fact that tensides in a chemical multi-componentmixture often only dissolve with great difficulty, which requires theaddition of solvents into the additive concentrate to preventseparation, i.e. deposit on the bottom of the additive container of thesupplier. This difficulty is also easily solved by the inventive method,which provides the possibility of applying only those chemical substancecomponents which are absolutely necessary for the printing process.Since the sheet speeds of modern printing machines are constantlyincreasing, increasingly precise measurement and dosing of theindividual chemical components are required. The inventive method istherefore essential to printing without alcohol. This is supported bythe fact that, with exactly the same printing machine, the compositionof the individual components of the additive must be variable—dependingon the printing orders i.e. on the paper, the particular inks requiredby the specific customer, the specially used rubber blanket, the rollercoating, etc. This is only possible with the new method describedherein. This is particularly true since there is no single conventionaladditive anywhere in the world which permits printing without alcoholunder all conditions that occur in a printing machine. This explains whyprinting managers want to repeatedly test other additive formulations torealize their printing orders. Nevertheless, each chemical formulationis a compromise and is therefore optimum only for a limited range ofprinting orders. In total, the current conventional procedure is veryexpensive and renders printing without alcohol impossible in practice,despite the above-mentioned legal regulations in Europe.

Conventionally, dosing means are used for generating the process liquidby volumetrically mixing the two or three components through controlunder fixed predetermined conditions and introducing them into theliquid circuit of the printing machine in accordance with the respectiveconsumption, i.e. in accordance with discharge of the liquid to thepaper being printed. In addition to mixing stations, which are operatedby hand, systems with conventional dosing pumps are also currently used.A severe disadvantage of these systems is that neither malfunctions ofthe mixing means nor changes in the physical and/or chemicalcomposition, e.g. due to chemical reactions or absorption or desorptionprocesses by the printing ink, paper, the pipe conduit or machinemodules, can be defined. In particular, evaporation processes produceconsiderable concentration errors in these classical dosing methods. Thesensors for detecting the electrical conductance which are currentlyused as sole control instruments are unsuitable for quantitativemeasurement of the concentration of the respective additive orsubstitute, due to the strong and varying soiling of the process liquid.Moreover, the important conducting chemical components of the additiveswhich permit printing cannot be detected through conductancemeasurements, since these substances cannot be dissociated in water. ThepH probe which has been introduced more or less as a standard in offsetprinting can at most be used as an indicator shortly before thefunctional collapse of the printing process, since the required strongchemical buffering of the process liquid e.g. using citric acid,prevents change of the pH value even for large variations in thechemical composition.

The object of the present invention is therefore the readjustment to therespective target values through continuous measurement and regulationof the composition of the dampening solution, i.e. through continuousredosing of the individual, differently decreasing chemical componentsor selected groups of components, to increase the up-time of the offsetprinting process to values of competing gravure printing, i.e. toapproximately 90 to 95%.

SUMMARY OF THE INVENTION

This object is achieved in accordance with the invention with a methodof the above-mentioned type in that spectroscopic methods are used formeasuring the components. The invention also provides measuring meanswith at least one spectrometer to solve the above-mentioned object in adevice of the above-mentioned kind.

In accordance with the invention, a method and a device are used inprinting technology which, for the first time, continuously measure theconcentrations of the individual components of the additive due toselective attenuation of electromagnetic radiation, and regulate theseto predetermined optimum values, thereby preventing losses in processliquid as well as overdosing of individual components of the additivesuch that the printing process can be continuously carried out with highstability and availability at an optimum working point. The selectivityof the measurement and regulation of the additive can be maintained notonly for alcohol-free printing, i.e. with substitutes, but also inprinting with admixtures of alcohol, since the alcohol does not falsifymeasurement of concentrations of the individual components of theadditive. This is of main inventive importance. In accordance with theinvention, the selective measurement of concentrations of the individualcomponents or of groups of different chemical compounds is coupled to adosing system which removes the various components from variouscontainers via a system comprising cycled valves and pumps, and guidesthem in a controlled manner to the dampening solution. This new methoddecisively optimizes offset printing with alcohol. Printing withoutalcohol is initially provided on a basis which permits long termprocessing, thereby meeting the economic boundary conditions. The factthat the new method permits individual, online adjustment of thedampening solution to the respective printing order, i.e. paper type,ink type, sheet speed and other fundamental interactions between the inkand dampening solution in the offset process, prevents generally knownproblems, such as e.g. inadmissible deposits on the rubber blanket,undesired ink decomposition in the dampening solution, detrimentalchemical etching of the printing plates etc. In particular, theinsufficient variation possibilities for the concentrations of theindividual chemical components of ready-to-use additives can bearbitrarily extended by the new method. Repeated dampening solutionexchange, in particular due to the above-mentioned search for betterdampening solution additives, the associated printing process down-timeof several hours, the corresponding negative consequences associatedwith the disposal of the previously used dampening solution, and theassociated disadvantageous effects on the overall economics of theprinting process, are avoided by the new method.

The invention permits qualitative, continuous measurement and regulationof the concentrations of the individual components of the respectiveadditive or the substitute in a matrix of up to 20 chemical componentswithout falsifying influence of other substances such as e.g. inparticular alcohols, dirt, ink and paper particles, gas bubbles, saltsfrom the paper and other impurities, as are typical for offset printing.Moreover, in accordance with the invention, the individual componentscan be measured and regulated with an accuracy between 10 ppm and 3.0%depending on the substance, since the different chemical contents of astatically predetermined additive mixture are not consumed in proportionto the concentration and the mixture consequently changes during theprinting process, since the inks, the paper and also other effectsproduce a more or less selective depletion of the individual components.The present invention completely compensates for the depletion effects,produced in particular during offset printing, irrespective of thecustomer order input into the printing machine. The present inventionsolves the above-stated objects, in particular, in that the individualchemical components are continuously measured by a spectrometer and aresupplied, in a controlled manner, to the dampening agent circuit in theform of pure, raw materials and/or as partial mixtures of severalcomponents, generally mixed with water, such that they easily dissolvein the dampening solution and, in particular, form no separate phases.In this way, chemical formulations may also be used which separate in apredetermined additive concentrate and therefore would not have led to ahomogeneous solution. In accordance with the invention, the attenuationof electromagnetic radiation during passage through the dampeningsolution is utilized for determining the concentration.

While components to be measured are generally detected in the infraredrange, in a preferred embodiment, the components to be measured aredetected in the ultraviolet range. It has turned out that an admissiblealcohol portion in the printing process liquid has no disturbing effecton the determination of the additive concentration in the UV range.

It has also turned out that, as mentioned above, the concentration ofthe components in the process liquid generally changes differently, i.e.vanishes in different amounts, during the printing process. However,individual components substantially vary in the same percentage amounts.To simplify the method and the inventive device, in one preferredembodiment, only the actual concentration of a part of the measuredcomponents is determined through the spectroscopic measurement ofcomponents, wherein the device comprises a concentration determiningunit, preferably including a computer, and structured in such a mannerthat merely the concentration of part of the components can bedetermined.

For the above-mentioned reason, a further preferred embodimentdetermines the actual concentration of at least one representativecomponent of a subgroup of components which are depleted in identicalamounts during the printing process, and the components of the subgroupare redosed together. This can be effected in different ways. Theindividual components may all be separate such that the dosing elementsreceive only one uniform dosing signal determined by the above-mentionedmeasurement for the mentioned subgroup of components. Alternatively, asubgroup of components of the additives may also be present in a dosingcontainer in the form of a partial mixture and can be dosed as such onthe basis of the dosing signal derived from the concentrationdetermination of the representative component. Towards this end, theinventive device has a control means for redosing a subgroup ofcomponents on the basis of the determined concentration of at least onecomponent of the subgroup.

The concentrations of a partial group of components may be depleted in asimilar but not identical manner such that, under certain circumstances,it may not be reasonable to measure the actual concentration of acertain component as a representative measurement, rather to determinethe concentrations of all components of the partial group or certaincomponents of the partial group and to assign a weighted average of thedepleted concentration or to first perform an individual comparisonbetween the actual concentration and a target concentration of theindividual components and subsequently determine an average value of thevanished amount for use as a control signal in redosing, in particular,of a mixture of the components of the above-mentioned partial group.Accordingly, a preferred embodiment of the invention provides that, fora partial group of components, the amount to be redosed of a mixturecontaining the components is determined from individual measurements ofthe components, and the partial group of components is redosed in theform of a mixture, wherein the device in accordance with the inventioncomprises means for performing individual measurements of the componentsto determine an amount to be redosed of a mixture containing a partialgroup of components, and for redosing the partial group of components inthe form of a mixture.

The individual spectra of the components are determined from themeasured overall spectrum using conventional mathematical methods, suchas e.g. by the method of the least squares (PLS=partial least squarealgorithm). Samples of different individual components are recorded by aspectrometer for calibration purposes. A calibration function can bedetermined for each component and used during operation to determine theconcentration loss of the respective components in a later measurement.A group concentration for groups of individual components or even theoverall concentration of an additive consisting of several individualcomponents can be determined therefrom, which, within the scope of theinventive method, can be redosed in total as such.

Alternatively thereto, the maximum of the sum of all partial spectra ofall components can be detected as an actual value. In an advantageousembodiment, the integral of the detected sum spectrum is determined andfurther processed as a measure of the overall concentration of theadditives.

In a preferred embodiment, the process liquid is guided through a flowchannel for spectral analysis, in which the measuring process takesplace to permit continuous measurement. In particular, electromagneticradiation may thereby be guided through the process liquid in andirection orthogonal to the flow surface. Towards this end, themeasuring means comprises at least one sample chamber for interactionbetween the process liquid and the electromagnetic radiation, whereinthe sample chamber comprises a flow channel through which the processliquid is guided, and wherein the optical path of the electromagneticradiation is orthogonal to the flow surface of the process liquid. In apreferred embodiment, the flow channel is formed to taper in the centralarea in the flow direction, thereby increasing the flow velocity andavoiding deposit of dirt in the sample chamber. In a highly preferredembodiment, the flow channel is formed as a Laval nozzle having aminimum nozzle cross-section of between 0.5 mm and 3 mm. In accordancewith the invention, the absorption spectrum of the components to bemeasured in the process liquid can preferably be detected.

BRIEF DESCRIPTION OF THE DRAWING

The invention is described in detail below with reference to thefigures.

FIG. 1 a shows UV spectra of a printing process liquid with freshadditive and after a certain operating period;

FIG. 1 b shows a difference spectrum of the two spectra of FIG. 1 a;

FIG. 2 shows the overall system consisting of measuring and regulationsystems, printing machine and process liquid circuit, wherein thedifferent chemical components/component groups are dosed directly by themeasuring and regulation device;

FIG. 3 shows a schematic view of the inventive measuring system;

FIG. 4 a shows a perspective front view of a preferred embodiment of theinventive sample chamber;

FIG. 4 b shows a perspective rear view of the inventive sample chamberof FIG. 4 a;

FIG. 4 c shows a section of the inventive sample chamber of FIG. 4 b;

FIG. 4 d shows a section of the inventive sample chamber of FIG. 4 a;

FIG. 4 e shows a side view of the inventive sample chamber of FIGS. 4 aand 4 b;

FIG. 5 shows an alternative embodiment of the invention, wherein dosingis effected using a Venturi nozzle;

FIG. 6 shows an alternative embodiment of the invention which ischaracterized in that the individual chemical components are guidedthrough a static mixer;

FIG. 7 shows a further system variant wherein previous mixing iseffected in a separate container which is connected to the overallsystem, wherein the composition corresponds to the optimum mixing ratio;and

FIG. 8 shows a system, wherein the optimum composition is achieved viacalibrated dosing pumps.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows, by way of example, a UV spectrum of a printing processliquid provided with fresh additive—spectrum A—and after a certainoperating period—spectrum B. It is particularly obvious from FIG. 1 bthat both enrichment (spectrum over 0.0) as well as depletion (cleardrop below 0.0 in the region close to 190 nm) are possible, depending onthe component. This is due to the fact that individual components aredischarged by the paper sheet to the process liquid during the printingprocess, while others can be absorbed from the process liquid by thepaper sheet in different ways.

The concentration of the individual components can be determined fromthe spectrum of FIG. 1 a using conventional methods, such as the leastsquares method.

In accordance with FIG. 2, the process liquid (2) contained in a tank(1) is circulated through the printing machine (4) and back to the tank(1) via circulating pumps (3) and pipe conduits (5). The respectiveindividual chemical component concentrations of the additive arecontinuously measured by a measuring system (6). The predeterminedchemical components K1, K2, K3, . . . to Kn are fed into the processliquid (2) via pumps (7) and valves (8). The respectively requireddifferent desired concentrations of the chemical components K1 to Kn areassured in that the measuring system (6) continuously measures theactual concentrations and adds a corresponding amount of the respectivecomponent during regulation so that the actual value is equal to thespecified, desired value. This ensures that the additive components,which are constantly consumed by the printing process or removed fromthe walls of the printing line through chemical reactions or physicalabsorption processes, are added to the process liquid (2) such that theactual values of the concentration of the additive are equal to thedesired values defined by the printer and irrespective of the strengthof the respective loss processes. The water loss in the process liquid(2) is compensated for via a pipe conduit (9), wherein the fill level(10) is kept constant using a level measuring and regulation system (11)in accordance with the ultrasound echolot principle or anotherconventional method. The concentration of the alcohol in the processliquid (2) (unless printing is effected without alcohol) is continuouslymeasured using a further measuring and regulation means (12) which mayalso be integrated into the measuring system (6) in accordance withanother design of the invention, and the alcohol loss causedsubstantially through evaporation is fed from a supply container (13)via a unit comprising a valve and dosing pump (14) such that the desiredand actual values are always the same and the availability and qualityof the printing process are also ensured for printing with alcohol. Astirring apparatus (15) is used to homogenize the process liquid.

FIG. 3 schematically shows an inventive measuring means (6). Theinventive measuring means (6) initially comprises an illumination unit(6.1) in the form of a lamp which is an infrared lamp for IRspectroscopy and a UV lamp for UV spectroscopy. An optical path (6.2),e.g. in the form of an optical fiber which may also be suitable forguiding UV light in UV spectroscopy, extends from the illumination unit(6.1) to a sample chamber (6.3). This may be a sample chamber in thesupply container (1) or a transparent tube piece in the line (5) betweenthe supply container (1) and the printing machine. Another optical path(6.4), also in the form of optical fibers, extends from the samplechamber (6.3) to an optical configuration (6.5) which has, inparticular, a slit. In the present embodiment, this is a gratingspectrometer (6.6) comprising an optical grating (6.7) which isassociated with a receiver configuration (6.8), in the presentembodiment, a diode line. In principle, a prism spectrometer can also beused instead of a grating spectrometer.

The signals which were opto-electronically converted by the receiverunit (6.8) are supplied to an electrode unit (6.9). It includes, inaddition to a computer, a regulation unit for comparing the actual anddesired concentrations, a determining means for determining the amountsof the components to be redosed, and a control means for redosing therespective components.

The individual components of the additives in the process liquid aredetected by the spectrometer, wherein the concentrations of thecomponents can be determined through calibration using the obtainedspectrum. These are also compared with the desired componentconcentrations in the electronics, whereupon, in case of differences,the amount of components to be redosed per unit time is determinedfollowed by redosing of the corresponding components. This may beinitially performed in that, as shown in the figures, the components areeach contained in individual component containers (K1, K2, . . . ) fromwhich the supply containers (1) are individually supplied in a mannerdescribed with reference to FIGS. 1 and 3 through 7.

FIG. 4 a shows a perspective exploded view of a preferred embodiment ofthe inventive sample chamber (6.3). It comprises a carrier element(6.3.1), an intermediate element (6.3.2) and a covering element (6.3.3).In the operative state of the sample chamber (6.3), these threecomponents are rigidly screwed to each other using the threaded screws(6.3.4) provided on the covering element (6.3.3) for this purpose, andthe associated threaded holes (6.3.6) provided in the carrier element(6.3.1) and the through holes (6.3.5) provided in the intermediateelement (6.3.2) in such a manner that the inner surface (6.3.3 a) of thecovering element (6.3.3) and the inner surface (6.3.1 a) of the carrierelement (6.3.1) form a continuous liquid-tight connection with eachouter surface (6.3.2 a) and (6.3.2 b) of the intermediate element(6.3.2). Towards this end, the intermediate element (6.3.2) ispreferably formed from hard PVC, and the surfaces (6.3.1 a) and (6.3.3a) as well as (6.3.2 a) and (6.3.2 b) contacting one another in pairsare preferably smoothed by polishing. To provide a continuousnon-positive connection between the respective contacting surfaces, in apreferred embodiment, at least eight threaded screws (6.3.4) and atleast eight associated threaded holes (6.3.6) are disposed in thecarrier element (6.3.1) and at least eight associated through holes(6.3.5) are disposed in the intermediate element (6.3.2). Alternatively,the through holes (6.3.5) may also have a thread with positive fitcorresponding to the threaded screws (6.3.4).

The carrier element (6.3.1) comprises an inlet bore (6.3.7) forsupplying the process liquid (2) into the sample chamber (6.3), intowhich the process liquid (2) is supplied via a connecting element(6.3.8) having an inner tubular shape, e.g. by a connected tube line(not shown) or through direct supply. An outlet bore (6.3.9) has afurther connecting element (6.3.10) disposed on the rear side for e.g. ahose pipe (not shown) in the carrier element (6.3.1) for discharging thesupplied process liquid (2) after the measuring process.

The actual measuring chamber (6.3.11) of the sample chamber (6.3) isformed by the intermediate element (6.3.2), which, towards this end, hasan opening (6.3.11) disposed on the end side at the level of the inletbore (6.3.7) and outlet bore (6.3.9) respectively, and adjusted to therespective bore periphery (6.3.7) and (6.3.9), which serves as a flowchannel between supplied and discharged process liquid (2). In a furtherdevelopment of the invention, the opening (6.3.11) is tapered in thecentral area. In a preferred embodiment, the width of the flow channelformed in this manner in the outlet area where the process liquid (2)exits the inlet bore (6.3.7) in the flow direction has an initialconverging part with a minimum value in the center and an adjacent partthat diverges until it enters into the outlet bore (6.3.9).

In accordance with the invention, the light beam is coupled anddecoupled to the flow surfaces in an orthogonal direction. Towards thisend, the covering element (6.3.3) and the carrier element (6.3.1) areeach provided with a further bore (6.3.12) and (6.3.13) through each ofwhich one optical guide (6.2) and (6.4) is disposed, flush with theinner surface (6.3.3 a) and (6.3.1 a), for feeding or extracting themeasuring beam, such that it borders the upper or lower flow surface.The optical path of the measurement is formed by the thickness of theintermediate element (6.3.2) which is preferably in a range between 0.7mm and 5 mm.

The bores (6.3.12) and (6.3.13) are preferably disposed in such a mannerthat the optical path of the measuring beam extends through the centerof the flow channel, defined by the opening (6.3.11).

To exactly adjust the optical path during coupling or decoupling of themeasuring beam by the optical fibers (6.2) and (6.4), the sample chamber(6.3) is produced in such a manner that the bores (6.3.12) and (6.3.13)are produced in one drilling process when the three components (6.3.1),(6.3.2) and (6.3.3) are screwed together. For fixing the optical path,the covering element (6.3.3) preferably comprises at least two fixingpins (6.3.14) which are each introduced into bores (6.3.15) and (6.3.16)disposed both in the intermediate element (6.3.2) and carrier element(6.3.1), wherein these bores (6.3.15) and (6.3.16) are also producedafter the sample chamber (6.3) has been screwed together.

FIGS. 4 b and 4 e further explain the individual components of thesample chamber (6.3) using perspective rear and side views,respectively. FIG. 4 c and FIG. 4 d show a detailed section (I) and (II)of FIG. 4 b and FIG. 4 a, to further explain fixing of the optical fiber(6.4) in the carrier element (6.3.1). After production of the bore(6.3.13), the optical fiber (6.4) is inserted into the bore until itsend borders the inner surface (6.3.1 a) or projects slightly beyond it.It is then fixed using a special adhesive to also seal the bore (6.3.13)in a liquid-proof manner. After the special adhesive has hardened, theoptical fiber (6.4) is surface-ground, level with the inner surface(6.3.1 a). An analogous method step is provided for fixing the opticalfiber (6.2) in the covering element (6.3.3).

In an alternative manner, the above-described variations can beimplemented to measure, detect and dose the individual components aswell as to detect concentrations of a representative component for asubset of components and/or for adding a mixture of a subgroup ofcomponents to the supply containers.

FIG. 5 shows a sketch of the inventive arrangement which comprises aprinting machine (16), a dampening solution tank (17), dampeningsolution (18) with circulation (19) and chemical components K1 throughKn (20) which are operated via a Venturi nozzle (21) and a pump (22),which suctions chemical components K1 through Kn via valves (23) andfeeds them into the dampening solution (18), wherein the concentrationsof the chemical components are measured via the measuring and regulationsystem (6). The supply (25) of water with automatic level regulation andthe stirring apparatus (26) correspond to the arrangements of FIG. 2.

FIG. 6 shows an overall arrangement which consists of a printing machine(27), a dampening solution tank (28), dampening solution (29), ameasuring and regulation system (6), a stirring apparatus (31), watersupply (32) including fill level control (33), dampening solutioncirculation (34), and an additional static mixer (35). The dampeningsolution (29) which is passed through the circuit via the pump (36) ismixed, in the static mixer (35), with the chemical components K1 throughKn (37) which are supplied into the circuit (39) via the valves (38)such that both the measuring system (30) and the circuit (34) containhomogeneous liquid mixtures, such that the overall system of FIG. 6provides optimum functioning.

FIG. 7 shows a version of the invention which differs from the previousfigures and which is characterized by previous mixing of the chemicalcomponents K1 through Kn (42) with a water supply (41), in a mixingcontainer (40) via pumps (50 a). The arrangement considerably reducesthe regulation process of the measuring system (6) to obtain therespective desired concentrations of the chemical components K1 throughKn (42), such that the composition of the dampening solution (44) in thedampening solution tank (45) always has the predetermined desiredvalues, even over brief time intervals. Moreover, analogously to thestirring apparatus (46) in the dampening solution tank, a homogenizingmeans (39) is also used in the pre-mixing container (40). Thehomogenizing means (35) may also be a static mixer in accordance withFIG. 6. To prevent possible fill level problems during feeding of thepre-mixed liquid (47) into the dampening solution tank (45), the use ofa sensor (48), preferably in accordance with the ultrasound echolotprinciple, is of great importance. Circulation (49) of the dampeningsolution (44) to the printing machine (50) via the pump (49) is effectedanalogously to FIGS. 2 through 6.

FIG. 8 shows the simplest variant in accordance with the invention,wherein the chemical components K1 through Kn (51) are added via a valve(54) using calibrated dosing pumps (53) regulated by the measuringsystem (6) in accordance with the respective desired value of theindividual components. The fill level measurement (55) and the stirringapparatus (56) permit homogeneous mixing of the dampening solution (58)in combination with the water supply (57) which circulates in thecircuit (60) between the printing machine (61) and dampening solutioncooling device (62) via the circulating pump (59).

We claim:
 1. A method for continuously regulating an overallconcentration of alcohol and additives and/or concentrations of alcoholand additive components other than alcohol in a printing process liquidin a printing machine comprising a printing press liquid tank and asample chamber disposed within the printing press liquid tank, thesample chamber monitoring the concentration of components of additivesin a printing press liquid, the printing machine comprising: a carrierelement having an outer surface, a single inlet bore opening to theouter surface, a single outlet bore opening to the same outer surface,and an inner surface on an opposite side of the carrier element from theouter surface; a covering element having an outer surface, and an innersurface on an opposite side of the covering element from the outersurface; an intermediate element having first and second outer surfaces,and a measuring chamber open to both the first and, second outersurfaces the intermediate element being disposed between the carrierelement and the covering element such that the inner surface of thecarrier element is proximate the second outer surface of theintermediate element and the inner surface of the covering element isproximate the first outer surface of the intermediate element, whereinthe covering element further comprises an optical guide bore passingthrough the covering element such that an optical guide component passestherethrough from the covering element to the measuring chamber in theintermediate element, wherein the carrying element further comprises anoptical guide bore passing through the carrying element such thatanother optical guide component passes therethrough from the carryingelement to the measuring chamber in the intermediate element, and firstand second connecting elements, the first connecting element beingoperatively fluidly coupled to the carrier element and providing aprocess liquid to the measuring chamber through the inlet bore, thesecond connecting element being operatively fluidly coupled to thecarrier element to discharge the process liquid provided into themeasuring chamber through the outlet bore, wherein the measuring chamberis configured such that the only inflow to the measuring chamber isprocess liquid that flows through the inlet bore of the carrying elementand the only outflow from the measuring chamber is discharge of theprocess liquid through the outlet bore of the carrying element, whereina flow channel is formed by the measuring chamber in the intermediateelement, the inner surface of the carrying element and the inner surfaceof the covering element, the thickness of the flow channel defines anoptical path length and the flow channel has in a downstream directionwithin a place of the intermediate element an initial converging part,leading to an increase of flow velocity of process liquid providedtherethrough, and thereby preventing deposits of particles and dirtwithin the flow channel, the method comprising the steps of: providingthe printing process liquid through the flow channel, takingspectroscopic measurements of the printing process liquid with one of agrating spectrometer and a prism spectrometer to continuously determineactual concentrations of the additive components other than alcohol, andindividually redosing each of measured components other than alcohol,based on the determined actual concentration of the respectivecomponent, to obtain a predetermined target concentration for each ofthe components, wherein due to the spectroscopic measurements,electromagnetic radiation penetrates the printing process liquid andmoves in an orthogonal direction with respect to a surface of theprinting process fluid, whereby the flow channel, is formed by theintermediate element the thickness of which defines an optical pathlength and that the flow channel in a downstream direction within aplane of the intermediate element has an initial converging part,leading to an increase of the flow velocity and thereby preventingdeposits of particles and dirt within the flow channel, and wherein theadditive components other than alcohol are detected via thespectroscopic measurements in a specified ultraviolet range from 190 nmto 390 nm, wherein the step of taking spectroscopic measurements of theprinting process liquid comprises: providing the printing process liquidto the sample chamber, illuminating the sample chamber from one sidethereof with ultraviolet radiation, a first portion of which encountersthe printing process liquid and traverses through the sample chamber,illuminating an optical configuration, which comprises a structuredefining a slit, with the first portion of ultraviolet radiation thattraverses through the sample chamber, a second portion of theultraviolet radiation passing through the slit, providing the secondportion of the ultraviolet radiation upon one of an optical grating orprism which transmits a third portion of the ultraviolet radiation to areceiver configuration which determines the component concentration ofthe printing process liquid based upon the received third portion of theultraviolet radiation, continuously measuring a concentration of alcoholin the printing process liquid independent of the taking ofspectroscopic measurements of the printing process liquid tocontinuously determine actual concentrations of the components otherthan alcohol, and redosing consumed alcohol from an alcohol reservoirinto the printing process liquid, based on the measured concentration ofalcohol, to obtain a predetermined target concentration of alcohol inthe printing process liquid, whereby, only the concentration of thecomponents other than alcohol is obtained via spectroscopic measurementusing ultraviolet radiation.
 2. The method of claim 1, wherein only anactual concentration of a part of the components other than alcohol isdetermined by the spectroscopic measurement.
 3. The method of claim 1,wherein only parts of the measured components are redosed.
 4. The methodof claim 1, wherein an actual concentration of at least onerepresentative component is determined for at least one subgroup ofcomponents other than alcohol and components of the subgroup are redosedtogether.
 5. The method of claim 1, wherein an amount of a mixturecontaining the components other than alcohol to he redosed is determinedfrom individual measurements of the components for at least one partialgroup of components and the partial group of components is redosed as amixture.
 6. The method of claim 1, wherein an integral of a detected sumspectrum is determined and further processed as a measure for theoverall concentration of the additives.
 7. The method of claim 1,wherein different chemical components are contained in individualcontainers and redosing is effected via a measuring system whichcontinuously measures concentrations of the individual components or ofgroups thereof and redoses the individual components via a control loop.8. The method of claim 7, wherein redosing of individual chemicalcomponents from the individual containers is effected via pumps, whicheach have one valve connected in series.
 9. The method of claim 1,wherein the individual components are suctioned into a dampeningsolution circuit by a Bernoulli nozzle.
 10. The method of claim 1,wherein mixing of a dampening solution and of individual components areoptimized by a static mixer.
 11. The method of claim 1, whereinindividual components other than alcohol are premixed with water in apremixing container and a liquid content of the premixing container istransferred into a dampening solution container.
 12. The method of claim1, wherein each component has a single associated pump and with asingle, common upstream valve for dosing individual chemical components.13. The method of claim 1, wherein an absorption spectrum of the processliquid is measured.
 14. A device for regulating an overall concentrationand a concentration of components of alcohol and additives other thanalcohol in a printing process liquid in a printing machine comprising aprinting press liquid tank and a sample chamber disposed within theprint liquid tank, the sample chamber monitoring the concentration ofcomponents of additives in a printing press liquid, the printing machinecomprising: a carrier element, having an outer surface, a since inletbore opening to the outer surface, a single outlet bore opening to thesame outer surface, and an inner surface on an opposite side of thecarrier element from the outer surface; a covering element having anouter surface, and an inner surface on an opposite side of the coveringelement from the outer surface; an intermediate element having first andsecond outer surfaces, and a measuring chamber open to both the firstand second outer surfaces, the intermediate element being disposedbetween the carrier element and the covering element such that the innersurface of the carrier element is proximate the second outer surface ofthe intermediate element and the inner surface of the covering elementis proximate the first outer surface of the intermediate element,wherein the covering element further comprises an optical guide borepassing through the covering element such that an optical guidecomponent passes therethrough from the covering element to the measuringchamber in the intermediate element, wherein the carrying elementfurther comprises an optical guide bore passing through the carryingelement such that another optical guide component passes therethroughfrom the carrying element to the measuring chamber in the intermediateelement, and first and second connecting elements, the first connectingelement being operatively fluidly coupled to the carrier element andproviding a process liquid to the measuring chamber through the inletbore, the second connecting element being operatively fluidly coupled tothe carrier element to discharge the process liquid provided into themeasuring chamber through the outlet bore, wherein the measuring chamberis configured such that the only inflow to the measuring chamber isprocess liquid that flows through the inlet bore of the carrying elementand the only outflow from the measuring chamber is discharge of theprocess liquid through the outlet bore of the carrying element, whereina flow channel is formed by the measuring chamber in the intermediateelement, the inner surface of the carrying element and the inner surfaceof the covering element, the thickness of the flow channel defines anoptical path length and the flow channel has in a downstream directionwithin a place of the intermediate element an initial converging part,leading to an increase of flow velocity of process liquid providedtherethrough, and thereby preventing deposits of particles and dirtwithin the flow channel, the device comprising: means forspectroscopically measuring the components other than alcohol; means fordetermining actual concentrations of the components other than alcohol;means for individually redosing each of the measured components otherthan alcohol, based on the determined actual concentrations of therespective component, to obtain a predetermined target concentration foreach of the components; means for guiding a printing process liquid flowthrough a channel which is formed by an intermediate element thethickness of which defines an optical path length; means for guidingelectromagnetic radiation to penetrate the printing process liquid andmove in an orthogonal direction with respect to the surface of theprinting process liquid; means for forming an initial converging part ofthe flow channel in downstream direction by an intermediate element toincrease the flow velocity in order to avoid deposits within the flowchannel, wherein the spectroscopic measuring means comprises at leastone spectrometer which detects compounds in the ultraviolet range from190 nm to 390 nm, and wherein the means for spectroscopically measuringthe components other than alcohol comprises the sample chamber forreceiving the printing process liquid, an illumination unit whichilluminates the sample chamber from one side thereof with ultravioletradiation, a first portion of which traverses through the printingprocess liquid and the sample chamber, an optical configuration whichcomprises a structure defining a slit which is illuminated by the firstportion of the ultraviolet radiation, wherein a second, portion of theultraviolet radiation passes through the slit, one of an optical gratingor prism having the second portion of the ultraviolet radiation directedthereon which transmits a third portion of the ultraviolet radiation toa receiver configuration which determines the component concentration ofthe printing process liquid based upon the received third portion, ofthe ultraviolet radiation; and an alcohol measuring and regulation unitthat continuously measures a concentration of alcohol in the printingprocess liquid independent of the measurement of the components otherthan alcohol by the means for spectroscopically measuring thecomponents, and that redoses consumed alcohol from an alcohol reservoirinto the printing process liquid based on the measured concentration ofalcohol in the printing process liquid, whereby, only the concentrationof the components other than alcohol is obtained via spectroscopicmeasurement using ultraviolet radiation.
 15. The device of claim 14,further comprising a control loop.
 16. The device of claim 15, furthercomprising a control means for redosing a subgroup of components otherthan alcohol on a basis of determined concentrations of at least onecomponent of said subgroup.
 17. The device of claim 15, furthercomprising means for determining a redosing amount of a mixturecontaining a partial group of components other than alcohol on a basisof individual measurements of said components and means for redosing thepartial group of components as a mixture.
 18. The device of claim 15,wherein a Bernoulli nozzle is used as a pump and is operated by apartial flow of a dampening solution circulated by a pump.
 19. Thedevice of claim 15, wherein chemical components other than alcohol arehomogeneously mixed with a. dampening solution using a static mixer in acircuit which is driven by a pump.
 20. The device of claim 15, whereinindividual chemical components other than alcohol are prepared in apremixing container with water from a water line via pumps and a mixtureis subsequently supplied to a main container.
 21. The device of claim15, wherein each individual chemical component is dosed into a dampeningsolution via a respective pump and with an upstream valve.
 22. Thedevice of claim 15, further comprising a pump having an upstream valvecoupled to the alcohol reservoir and being controlled by the alcoholmeasuring and regulation unit to redose consumed alcohol into theprinting process liquid.
 23. The device of claim 15, wherein said flowchannel has a shape of a Laval nozzle.
 24. The method of claim 1,further comprising the step of providing the ultraviolet radiation via afirst optical fiber from an illumination unit to the sample chamber. 25.The method of claim 1, further comprising the step of providing thefirst portion of the ultraviolet radiation via a second optical fiberfrom the sample chamber to the optical configuration.
 26. The device ofclaim 14, further comprising a first optical fiber operatively couplingthe illumination unit and the sample chamber to provide the ultravioletradiation from the illumination unit to the sample chamber.
 27. Thedevice of claim 14, further comprising a second optical fiberoperatively coupling the sample chamber and the optical configuration toprovide the first portion of the ultraviolet radiation from the samplechamber to the optical configuration.